The present invention relates to a method and device for removing oil, for example removing oil spills either from hard surfaces or from floating on a body of water, by both absorbing and transporting the oil, optionally via a pump, to a holding tank or reservoir.
U.S. Pat. No. 5,834,385, issued on Nov. 10, 1998, discloses a nonwoven hydrophobic web which encases an absorbent core, the whole article being of use to dear up oil spills. Pore sizes of the nonwoven hydrophobic web are not disclosed,
U.S. Pat. No. 5,885,451, issued on Mar. 23, 1999, discloses a fibrous material (fabric, paper, sponge, sheet or film) which is impregnated or coated with oleophylic, hydrophobic composition. The fibrous material is used to absorb oil which may then be wrung out of the material in order to recover the oil for storage, for example on board a ship, so that the material can then be reused.
Both of these prior art oil absorbent articles are designed to absorb oil, for example from a spill, and when saturated with oil, the absorbent article is removed from the oil source or spill, and either simply discarded or destroyed, e.g. by burning, or else the oil is squeezed out of the apparatus so that the apparatus might be reused and/or so that the oil might be recovered. Squeezing the oil out of the apparatus, such as illustrated in FIG. 14 of U.S. Pat. No. 5,885,451, is a cumbersome, time-consuming and expensive operation.
It is an object of the present invention to remove oil from an oil source or spill by continuously extracting the oil from the oil source or spill and transporting it to a holding reservoir or tank. Such a process would be much more economical than the prior art processes of removing the oil from the saturated absorbent article, and would enable much quicker removal of oil. Quick removal of the oil is a very important factor especially in the case of oil spillage at sea or in a port following an emergency such as an oil discharge from an oil tanker. In recent years such discharges, especially accidents involving oil tankers at sea, have had a detrimental effect on the maritime environment and wildlife, and attempts to clean up such discharges have been very expensive and only partially successful.
One aspect of the present invention provides a method comprising the steps of: absorbing the oil into a bulk material, the bulk material having an inlet region and an outlet region, by passing the oil into the inlet region of the bulk material through a membrane; and removing the oil from the outlet region of the bulk material. A second aspect of the present invention provides an oil removal and transport device comprising a bulk material, the bulk material comprising an inlet region and an outlet region.
The method of the present invention uses a membrane having an average pore size not greater than 100 micrometers so that the oil is continuously transported through the membrane into the inlet region of the bulk material and continuously removed from the outlet region of the bulk material into a reservoir.
The device of the present invention comprises a reservoir which is in liquid communication with the outlet region and the device further comprises a membrane hermetically sealed to or about the inlet region, the membrane being liquid permeable and having an average pore size not greater than 100 micrometers.
Preferably the membrane is oleophylic and has a bubble point pressure of at least 1 kPa, preferably from 2 kPa to 100 kPa, and more preferably from 8 kPa to 50 kPa, when measured at ambient temperature and pressure using 0.03% solution of Triton X-100 in distilled water as the standard test liquid.